He says almost exactly what I posted. He's walking through it there, but it's been done before with guys playing receiver and QB in the same season. When Danny Barrett first came into the league he played both receiver and QB for the Stamps. How the league manages a team trying to hide a QB in another roster designation is by the rule that someone designated a QB has to be on the field for each offensive play. So if you dressed Streveler as a DI, he'd have to both sub in for another import, and you'd have to have one of the 2-3 guys rostered as QB's on the field, and you can only have one QB on the field for offensive plays. So unless you have another QB who is a CFL-level receiver, you're playing at a pretty significant deficit.
Often when the rosters were smaller, like when it was a 36 man roster, teams would dress their kickers as the 3rd QB as it has no effect on special teams.